Single gear-pair vehicle differential

ABSTRACT

A differential for motor vehicles uses a crown or ring gear attached to a drive shaft to drive a single pinion gear attached to a first axle half shaft positioned at right angles to the drive shaft. In one embodiment, a second opposing axle half shaft is allowed to free wheel within the differential case. In a second embodiment, the opposing axle half shaft is slippably driven by the first axle half shaft by means of a clutch coupling the first and second axle half shafts. 
     In a third embodiment, first and second axle half shafts are rigidly coupled to one another.

This application is a division of U.S. patent application Ser. No.674,263 filed Nov. 23, 1984, now U.S. Pat. No. 4,637,276.

BACKGROUND OF THE INVENTION

1. Field Of The Invention

This invention relates to differential assemblies for use in motorvehicles. More particularly, it relates to differential assemblieshaving an input drive shaft coupling and two colinear, opposed halfaxles extending perpendicularly outward from the input drive shaft axis.

2. Description Of The Prior Art

Conventional vehicle differentials generally employ an input pinion gearcoupled to the end of an input drive shaft which is rotated by thevehicle engine. In the conventional differential, the input pinion geardrives a crown or ring gear whose rotation axis is perpendicular to therotation axis of the input pinion gear. The crown or ring gear isrotably mounted coaxially over the inner end of one half axle. One wheelof the vehicle is mounted to the outer end of the half axle. A secondwheel and half axle are mounted at the opposite side of the vehicle.

A box-like structure differential housing or carrier referred to as thedifferential housing is mounted rigidly to the inner side of the crownor ring gear. The inner ends of both half axles extend inward throughopenings on opposite sides of the carrier, and are rotatably supportedthere within. Rigidly mounted to the ends of both half axles within thecarrier are side bevel gears which face inward. The side gears aresimilar in appearance to the crown or ring gear, but smaller. Meshing atright angles with the pair of side gears are two opposed pairs ofinwardly facing differential pinion gears which are rotatably mounted tothe carrier. The axes of the two opposed pairs of differential piniongears are perpendicular to one another and to the common axis of thehalf axles.

When a vehicle with a conventional differential as just describedtravels in a straight line, the crown or ring gear, differentialcarrier, side gears and attached half axles all rotate at the sameangular velocity. In that situation, the differential pinion gears donot rotate around their own axes.

However, when the vehicle turns, the axle half shaft attached to theoutward wheel turns faster than the axle half shaft attached to theinboard wheel. The accompanying relative rotational motion of the halfshafts with respect to one another is permitted by the rotation of thedifferential side gears with respect to one another, and with respect tothe differential carrier. This imparts a corresponding, opposed rotationcouple to each pair of opposed differential pinions about their ownaxes. The rotation of coaxial differential pinion gears pairs relativeto one another permits the two side bevel gears which mesh with thedifferential pinion gears and which are rigidly connected to the twoaxle half shafts to rotate with different speeds required for inboardand outboard wheels.

OBJECT OF THE INVENTION

An object of the present invention is to provide a vehicle differentialdesign having fewer gears than existing designs, thereby providing adifferential having potentially lower cost and weight.

Another object of the invention is to provide a vehicle differentialwhich may be readily modified to a locked axle configuration.

Another object of the invention is to provide a vehicle differentialproviding limited slippage, i.e., relative rotation between axle halfshafts driven through the differential.

Various other objects and advantages of the present invention, and itsmost novel features, will become apparent to those skilled in the art bya reading of the accompanying specification and claims.

It is to be understood that although the invention disclosed herein isfully capable of achieving the objects and providing the advantagesmentioned, the structural and operational characteristics of theinvention described herein are merely illustrative of the preferredembodiments. Accordingly, we do not intend the scope of our exclusiverights and privileges in the invention to be limited to the details ofconstruction described. We do intend that reasonable equivalents,adaptations and modifications of the various embodiments andmodifications of the present invention which are described herein areincluded within the scope of this invention as defined by the appendedclaims.

SUMMARY OF THE INVENTION

A vehicle differential according to the present invention uses a crownor ring gear as a drive gear fastened to an input drive shaft, ratherthan a pinion gear, which is used as the drive gear in a conventionaldifferential. Also, the present invention uses a pinion gear positionedat right angles to the drive shaft ring gear, rather than a crown orring gear, as the driven gear.

No differential carrier, differential pinion gears or differential sidegears are used in the present invention. Instead, a first axle halfshaft is rotatably mounted through one side of the differential case.The first axle half shaft is rotatably driven by a single pinion gearfunctioning as a side gear. The pinion gear is fastened to the inner endof the first axle half shaft, and is driven by the input ring gear.

A second, opposing axle half shaft is rotatably mounted through theopposite side of the differential case.

In one embodiment of the invention, the second opposing axle half shaftis allowed to free wheel within the differential case. In a secondembodiment of the invention, the second axle half shaft is slippablydriven by the first axle half shaft by means of a slip clutch couplingthe inner ends of the first and second axle half shafts. In a thirdembodiment of the invention, the inner ends of the first and second axlehalf shafts are rigidly coupled together, allowing no relative rotationof the axle half shafts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of the invention.

FIG. 2 is an exploded top plan view of the apparatus of FIG. 1.

FIG. 3 is a fragmentary, partially sectional rear elevation view of theapparatus of FIG. 1.

FIG. 4 is a sectional side elevation view of the apparatus of FIG. 1,taken along the line 4--4 in FIG. 3.

FIG. 5 is a fragmentary, partial sectional elevation view of a secondembodiment of the apparatus shown in FIG. 1.

FIG. 6 is a fragmentary, partially sectional rear elevation view of athird embodiment of the apparatus shown in FIG. 1.

FIG. 7 is a sectional side elevation view of the apparatus of FIG. 6,taken along line 7--7 in FIG. 6.

FIG. 8 is an exploded view of the clutch disc and plate assembly ofFIGS. 6 and 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIGS. 1 and 2, a vehicle differential constructed inaccordance with the present invention is shown. A bulbous metal shellforms the front portion of the case for the differential. A moregenerally flat, disc-shaped rear cover plate 12 encloses the backportion of the differential and is secured to the differential case bybolts 13.

Tubular axle housing cylinders 14 extend outward from either side ofdifferential case 11, and are rigidly fastened thereto. Wheel backingplates 15 and brake shoes 16 are shown fastened to the outer ends ofeach axle housing cylinder 14.

As may be seen best in FIGS. 1, 2 and 3, the conversion of inputrotational power, about the longitudinal input axis of the differential,to rotational power about the axis of the axle, perpendicular to thelongitudinal input axis, is accomplished primarily by driving sidepinion gear 17 by input ring or crown gear 18.

Ring gear 18 is rotated by a conventional longitudinal drive shaft 19 asfollows. Referring now to FIGS. 1 and 2, drive shaft 19, which is notpart of the present invention, is coupled to front half 20 of universaljoint 21, which is in turn pivotably connected to the rear yoke 22 ofthe universal joint. Rear yoke 22 is fastened with crown nut 23 to thethreaded hub end 24 of crown gear backing plate 25. Crown or ring gear18 is fastened to the back flat portion of crown gear backing plate 25by means of bolts 26. The hub shaft 27 of backing plate 25 is rotatablymounted through an opening in the front portion of differential case 11by means of opposed tapered roller bearings 28 and 29 rotating withinbearing caps 39 and 31, respectively.

As may be seen best in FIG. 3, crown or ring gear 18 faces rearward intothe interior of differential case 11 and meshes with side pinion gear 17which is fastened to the inner end of left axle half shaft 32. Althoughside pinion gear 17 could be fastened to either one of the axle halfshafts, according to present invention, it is shown fastened to the leftaxle half shaft 32 for purpose of illustration in the present example.

The inner end 33 of left half axle 32 is constricted to a smaller,uniform diameter section from the inner transverse face of the half axlesome distance back from that face. Back some distance from thetransition between the constricted diameter inner end 33 of left halfaxle 32 and the uniform diameter section extending outward towards theleft wheel backing plate, the left half axle has an externally threadedsection 34 disposed longitudinally some distance further back. Sidepinion gear 17 is secured to threaded section 34 of half axle 32 by locknut 35 tightened thereto. Safety snap ring 36 inserted transversely intoannular groove 37 in half axle 32 between inner end 33 and threadedportion 34 of left half axle assures that lock nut 35 will notinadvertently loosen from threaded section 34.

Left half axle 32 is rotatably supported through an opening in the leftside of differential case 11 by tapered roller bearing 38 rotating inbearing ring 39. Snap ring gear clip 40 inserted transversely intoannular groove 41 in left half axle 32 inboard of bearing 38 and bearingring 39 provides a backing support for gear shim 42. The longitudinalposition of left side pinion gear 17 relative to the center of crowngear 18 is adjusted by selecting the thickness of gear shim 42. Gearshim 42 bears against the face of side pinion gear 17 and is maintainedin position by snap ring gear clip 40.

As may be seen best in FIG. 3, right half axle 43 is rotatably supportedthrough an opening in the right side of differential case 11 by taperedroller bearing 44 rotating in bearing ring 45. Bearing ring 45 androller bearing 44 are secured to differential case 11 by means ofbearing cap 46 and bolts 47.

In the basic embodiment of the invention, a cylindrical cavity 48coaxial with the longitudinal axis of right half axle 43 extends backsome distance from the inner face of the right half axle. Cavity 48 isof sufficient diameter to permit inner end 33 of left half axle 32 torotate within the cavity without contacting right half axle 43.Alternatively, an annular bearing may be positioned between inner end 33and cavity 48. Holes 49 through the wall of cylindrical end cavity 48permit lubricant contained within differential housing 11 to pass intothe region between inner end 33 and cavity 48. Thus, in the basicembodiment of the invention, one half axle (the left half axle 32 inthis example) is driven, while the other half axle (the right half axle43 in this example) is permitted to free wheel. Therefore, when avehicle equipped with a differential according to the present inventionexecutes a left turning motion, right half axle 43 and the wheelattached to its outer end are free to rotate at the larger rotationspeed required for an outboard wheel. Conversely, when the vehicleexecutes a right turning motion, the right half axle and wheel are freeto rotate at the smaller rotation speed required for an inboard wheel.

An alternate embodiment of the invention generally in conformance withthe structure illustrated in FIGS. 1 through 4 is shown in FIG. 5. Inthe alternate embodiment shown in FIG. 5, the interior of cylindricalend cavity 48 of right half axle 43 is provided with internal splines50. End 33 of left half axle 32 is provided with external splines 51which permit end 33 to slide freely into cavity 48 during assembly ofthe differential. However, splines 50 and 51 mesh with one another toprevent relative rotation of left half axle 32 and right half axle 43.Thus, in this embodiment, left rear half axle 32 and right half axle 43are rigidly locked together and constrained to turn at the same rotationspeeds. This locked rear axle configuration is useful for suchapplications as drag racing.

In a third embodiment of the invention, shown in FIGS. 6, 7 and 8, aslip clutch is used to slippably couple rotary motion from the left halfaxle to the right half axle.

As shown in FIGS. 6 and 7, the inner end of right half axle 43 ismodified from the right half axle used in the basic embodiment of theinvention by the addition of a hollow cylindrical clutch housing 52fastened to the inner end of left half axle 32 just inboard of the pointwhere the left half axle protrudes into the interior of differentialcase 11. Clutch housing 52 is coaxial with the longitudinal axis of lefthalf axle 32, and extends inward some distance towards the center ofdifferential case 11. The walls of clutch housing 52 contain a pluralityof rectangular cross-section, elongated slots 53 disposed longitudinallyparallel to the longitudinal, cylindrical axis of clutch housing 52. Aplurality of identical uniformly spaced clutch driving plates in theshape of annular rings 54 are held captive within slots 53 of clutchhousing 52, as will be described below. Clutch driving plates 54 aredisposed in parallel alignment along and perpendicular to thelongitudinal axis of clutch housing 52. Clutch driving plates 54 arefabricated from thin, uniform cross section metal sheet stock.

Each clutch driving plate 54 is provided with a plurality of integralrectangular tabs 55 which extend radially outward from the outercircumferential edge of each plate. Tabs 55 protrude into correspondingslots 53 in clutch housing 52, thereby being driven rotationally byclutch housing 52.

Clutch driving plates 54 slippably drive clutch friction plates 56, aswill be described below. As shown in FIGS. 6 and 7, clutch frictionplates 56 are flat, annular shaped discs which are internally splined.Friction plates 56 are disposed along the externally splined inner endof right half axle 43, between pairs of clutch driving plates 54. Themesh between the externally splined surface of right half axle 43 andinternally splined surfaces of clutch friction plates 56 forces righthalf axle 43 to rotate at the same rate as friction plates 56.

The inner end of clutch housing 52 has an integral cup-shaped member 57coaxial with the longitudinal axis of the housing, and extending outwardtherefrom. An outward facing opening in cup-shaped member 57 is slidover end 33 of left half axle 32 during assembly of the differential.Cup-shaped member is secured rotationally to end of left half axle 32 bymeans of radially inward projecting splines 58 on member 57 meshing withcorresponding slots 59 on left half axle end 33, as shown in FIG. 6.Cup-shaped member 57 and attached clutch housing 52 are securedlongitudinally to left half axle 32 by a plurality of countersunk Allenscrews 60 screwed through holes 63 in cup-shaped member 57 and holes 64in left half axle 32.

Clutch friction plates 56 are caused to be frictionally driven by clutchdriver plates 54 by tightening internally threaded clutch adjustingcollar 61 over threaded portion 62 of right half axle 43 down onto theoutermost clutch driver plate 54. Facing surfaces of clutch frictionplates 56 and clutch driver plates 54 are laminated with thin sheets ofpaper or similar material which provides a relatively high coefficientof friction. The pressure applied to outermost clutch driver plate 54forces mating surfaces of clutch driver plates 54 and clutch frictionplates 56 to frictionally contact one another. Thus, when left half axle32 is rotatably driven, clutch housing 52, which is rigidly fastened toinner end 33 of left half axle 32 also rotates, along with clutch driverplates 54 rigidly attached to the interior of the clutch housing. Thepressure produced on the mating surfaces of clutch driver plates 54 andclutch friction plates 56 by clutch collar 61 causes friction plates 56to rotate at the same speed as driver plates 54. Also, the engagement ofsplines of friction plates 56 in slots of right half axle 43 causesright half axle to rotate along with friction plates 56, and hence atthe same speed as left half axle 32. Accordingly, when a vehicleequipped with a differential according to this embodiment of the presentinvention travels in a straight line both left and rear half axles turnat the same speed, and vehicle locomotion power is applied to both leftand rear half axles. When the vehicle executes a right turn, left halfaxle 32 must rotate faster than right half axle 43, since the outboardwheel of the vehicle and hence the half axle attached to it must rotatefaster than the inboard wheel and axle. Slippage between clutch drivingplates 54 and clutch friction plates 56 allows left half axle 32 anddriving plates 54 to rotate faster than driven friction plates 56 andright half axle 43. Conversely, when the vehicle executes a left turningmotion, the left half axle and wheel and clutch driving plates 54 arepermitted to rotate at a slower rate than right half axle 43 and drivenfriction plates 56, owing to the slippage between clutch driving plates54 and driven friction plates 56.

What is claimed is:
 1. An apparatus for transforming rotary power conveyable into said apparatus by a drive shaft to rotary traction power to at least one wheel of the vehicle comprising:a. a ring gear having a forward protruding hub adapted to rigidly couple to an input drive shaft, b. a beveled gear having longitudinally disposed teeth adapted to mesh with teeth of said ring gear, said teeth of said ring gear being located rearward of said ring gear hub, c. a first half axle rigidity coupled to said beveled gear, d. a second half axis colinear with said first half axle, said second half axle containing a blind cylindrical cavity having an opening sufficiently large to permit the inner end of said first half axle to rotate freely within said cylindrical cavity, said inner end of said first half axle fitting within said cavity and being supported by said second half axle, said beveled gear being mounted coaxially over said first half axle, back some distance from that inner end of said first half axle adjacent the inner end of said second half axle, e. means for rotatably supporting said ring gear and said first and second half axles comprising a bulbous shaped housing having a front opening and coaxial bearing assembly for rotatably supporting said hub of said ring gear, and first and second colinear side openings symmetrically disposed on either side of said housing, each of said side openings having a coaxial bearing assembly for rotatably supporting said first and second half axles, respectively, and means for rigidly coupling said beveled gear to said first half axle comprising in combination, (i) an externally threaded longitudinal section on said first half axle, said threaded section being located longitudinally outwards of said inner end of said first half axle rotatably disposed within the inner end of said second half axle, (ii) an annular groove in the outer cylindrical wall of said first half axle longitudinally outwards of said externally threaded section of said first half axle, said groove being located longitudinally adjacent an inner annular face of said coaxial bearing assembly rotatably supporting said first half axle, (iii) a generally annular lock ring lockingly engageable in said annular groove, and (iv) an internally threaded nut tightenable on said externally threaded section of said first half axle to apply an outward longitudinal force on the inner annular face of said beveled gear, thereby forcing the outer annular face of said beveled gear against the inner annular face of said annular lock ring, and thereby minimizing potential longitudinal movement of said first half axle relative to said housing and said coaxial bearing assembly.
 2. The apparatus of claim 1 further including a flat annular shim coaxially encircling said first half axle, said shim being located longitudinally between the inner annular face of said annular lock ring and the outer annular face of said bevelled gear, said shim being of thickness selected to maintain said bevelled gear in a desired longitudinal position.
 3. The apparatus of claim 2 further including a second annular groove in the outer cylindrical wall of said first half axle inwards of said externally threaded section of said first half axle, said groove being adapted to receive a generally annular locking ring to secure said threaded nut against inward longitudinal movement relative to said first half axle. 